Atrial tissue characterization by cardiac magnetic resonance and high-density mapping in patients with atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. BACKGROUND Left atrial fibrosis is a marker of atrial disease and it has an important role in the pathophysiology of atrial fibrillation (AF). Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) is an emerging tool to detect left atrial fibrosis. However, data on the correlation between LGE-CMR detected fibrosis and low voltage areas to define fibrotic tissue is scarce. PURPOSE To assess the correlation and degree of concordance between LGE-CMR and high-density bipolar voltage mapping for the identification of left atrial abnormal tissue. METHODS Seven patients scheduled for AF ablation (including first and redo procedures) underwent a preprocedural 1.5 Tesla LGE-CMR including left atrial 3D inversion-recovery steady-state free precession sequence (ECG and respiratory triggering) 20 minutes after the injection of 0.2 mmol/kg of gadobutrol. A high-density electroanatomical voltage mapping was acquired with a 16-electrode grid configuration mapping catheter during sinus rhythm. LGE-CMR studies were analyzed off-line with an advanced image post-processing tool (ADAS 3D). Atrial wall intensity was normalized to blood pool, obtaining an image intensity ratio (IIR) value for each CMR point of the 3D model. High-density bipolar voltage maps and LGE-CMR 3D left atrial reconstruction were merged (figure, panel A). Voltage points were projected to the LGE-CMR left atrial 3D model, allowing point-by-point correlation analysis between voltage (log transformed due to non-normal distribution) with IIR. Left atrial fibrosis area and percentage were quantified using the standard cut-off values (bipolar voltage <0.5mV and IIR >1.2). We assessed the degree of concordance for normal and abnormal (fibrosis) tissue classification between the two techniques using different cut-off values (< 0.5mV and <1mV for bipolar voltage and >0.9, >1, >1.1 and >1.2 for IIR). RESULTS The average fibrosis area detected with LGE-CMR was lower than that detected with high-density bipolar voltage, using standard cut-off values (18.6 ± 5.7 cm2 vs. 40.6 ± 12.5 cm2, p = 0.13 respectively). There was a poor global point-by-point correlation between log-transformed voltage and IIR was r=-0.093, p < 0.001 (figure, panel B). The best concordance was obtained when using bipolar voltage and IIR of 0.5mV and 1.2, respectively (64.7 %; Kappa 0.101). However, the highest kappa index (0.142) for concordance was achieved with cutoff values of bipolar voltage <1mV and IIR >1, with an agreement percentage of 54.6%. CONCLUSIONS Left atrial tissue characterization between LGE-CMR and high-density bipolar voltage mapping showed significant but poor point-by-point correlation. Although the highest concordance was obtained using standard cutoff values, the Kappa index was best when applying non-standard cutoffs (1mV for bipolar voltage and >1 for IIR). Abstract Figure.

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Voltage mapping as a method of left atrial fibrosis evaluation

Patologiya krovoobrashcheniya i kardiokhirurgiya ◽

10.21688/1681-3472-2016-2-111-116 ◽

2016 ◽

Vol 20 (2) ◽

pp. 111 ◽

Cited By ~ 1

Author(s):

O. V. Sapelnikov ◽

Yu. A. Shuvalova ◽

D. Yu. Cherkashin ◽

A. A. Krupnov ◽

A. S. Partigulova ◽

...

Keyword(s):

Atrial Fibrillation ◽

Left Atrial ◽

Large Scale ◽

Atrial Fibrosis ◽

Instrumental Data ◽

Voltage Mapping ◽

Special Software ◽

Mechanisms Of Development ◽

Left Atrial Fibrosis ◽

And Control

Aim: This pilot study is designed to better understand the mechanisms of development and control of atrial fibrillation. Methods: The correlation between fibrosis index (FI), which was calculated intraoperatively with special software, and clinical and instrumental data was analyzed. Also evaluated were FI values as compared to AF catheter ablation outcomes. Results: Voltage mapping may be considered as a possible alternative to MRI examination and in some cases it is more informative. Conclusion: It was found out that the preliminary results received are a good start for planning a large-scale study in this area related to assessment of the predicative and practical value of the fibrosis index.

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P828Quantitative assessment of left atrial fibrosis in patients with paroxysmal atrial fibrillation using high density Confidense mapping

EP Europace ◽

10.1093/europace/euy015.432 ◽

2018 ◽

Vol 20 (suppl_1) ◽

pp. i152-i153

Author(s):

D Asvestas ◽

K Letsas ◽

G Bazoukis ◽

A Saplaouras ◽

C Goga ◽

...

Keyword(s):

Atrial Fibrillation ◽

Paroxysmal Atrial Fibrillation ◽

Left Atrial ◽

High Density ◽

Atrial Fibrosis ◽

Left Atrial Fibrosis

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Comparison of Unipolar and Bipolar Voltage Mapping for Localization of Left Atrial Arrhythmogenic Substrate in Patients With Atrial Fibrillation

Frontiers in Physiology ◽

10.3389/fphys.2020.575846 ◽

2020 ◽

Vol 11 ◽

Author(s):

Deborah Nairn ◽

Heiko Lehrmann ◽

Björn Müller-Edenborn ◽

Steffen Schuler ◽

Thomas Arentz ◽

...

Keyword(s):

Atrial Fibrillation ◽

Left Atrial ◽

Low Voltage ◽

High Density ◽

Border Zone ◽

Electrode Spacing ◽

Bipolar Voltage ◽

Voltage Mapping ◽

Arrhythmogenic Substrate ◽

The Impact

Background: Presence of left atrial low voltage substrate in bipolar voltage mapping is associated with increased arrhythmia recurrences following pulmonary vein isolation for atrial fibrillation (AF). Besides local myocardial fibrosis, bipolar voltage amplitudes may be influenced by inter-electrode spacing and bipole-to-wavefront-angle. It is unclear to what extent these impact low voltage areas (LVA) in the clinical setting. Alternatively, unipolar electrogram voltage is not affected by these factors but requires advanced filtering.Objectives: To assess the relationship between bipolar and unipolar voltage mapping in sinus rhythm (SR) and AF and identify if the electrogram recording mode affects the quantification and localization of LVA.Methods: Patients (n = 28, 66±7 years, 46% male, 82% persistent AF, 32% redo-procedures) underwent high-density (>1,200 sites, 20 ± 10 sites/cm2, using a 20-pole 2-6-2 mm-spaced Lasso) voltage mapping in SR and AF. Bipolar LVA were defined using four different thresholds described in literature: <0.5 and <1 mV in SR, <0.35 and <0.5 mV in AF. The optimal unipolar voltage threshold resulting in the highest agreement in both unipolar and bipolar mapping modes was determined. The impact of the inter-electrode distance (2 vs. 6 mm) on the correlation was assessed. Regional analysis was performed using an 11-segment left atrial model.Results: Patients had relevant bipolar LVA (23 ± 23 cm2 at <0.5 mV in SR and 42 ± 26 cm2 at <0.5 mV in AF). 90 ± 5% (in SR) and 85 ± 5% (AF) of mapped sites were concordantly classified as high or low voltage in both mapping modes. Discordant mapping sites located to the border zone of LVA. Bipolar voltage mapping using 2 vs. 6 mm inter-electrode distances increased the portion of matched mapping points by 4%. The unipolar thresholds (y) which resulted in a high spatial concordance can be calculated from the bipolar threshold (x) using following linear equations: y = 1.06x + 0.26mV (r = 0.994) for SR and y = 1.22x + 0.12mV (r = 0.998) for AF.Conclusion: Bipolar and unipolar voltage maps are highly correlated, in SR and AF. While bipole orientation and inter-electrode spacing are theoretical confounders, their impact is unlikely to be of clinical importance for localization of LVA, when mapping is performed at high density with a 20-polar Lasso catheter.

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P1010Association between left atrial fibrosis detected by cardiac magnetic resonance and endocardial electroanatomic mapping in the evaluation of the electrophysiological substrate in atrial fibrillation

EP Europace ◽

10.1093/europace/euaa162.068 ◽

2020 ◽

Vol 22 (Supplement_1) ◽

Author(s):

G Caixal ◽

F Alarcon ◽

M Nunez ◽

P Garre ◽

D Soto ◽

...

Keyword(s):

Atrial Fibrillation ◽

Magnetic Resonance ◽

Left Atrium ◽

Conduction Velocity ◽

Left Atrial ◽

Inverse Correlation ◽

High Density ◽

Atrial Fibrosis ◽

Reproducible Method ◽

Left Atrial Fibrosis

Abstract Background Atrial fibrillation (AF) is related to left atrial fibrosis, but its identification by late magnetic resonance imaging (LGE) with gadolinium (LGE) persists in controversy due to heterogeneous results in its correlation with the electroatomic map (EAM) and the difficulty of perform histological studies in humans. Purpose We try to examine the point-by-point association between high density EAM and LGE-MRI using an automatic and reproducible method. Methods A LGE-MRI was performed in 16 patients prior to ablation. Three different areas were established depending on the intensity of normalized enhancement for each patient according to their blood group with the image intensity ratio (IIR) (healthy <1.20, border area (BZ) ≥1.20 <1.32 and scar ≥1.32). The high density electroanatomic maps of the left atrium (LA) were projected onto the MRI, obtaining an automatic correlation point by point. Results The study obtained significant differences (p < 0.001) between voltage (mV) and CV (mm/ms) among healthy, BZ and scar areas, as well a significant inverse correlation (p < 0.001) between voltage and IIR (R=-0.39). It obtained too a significant correlation between CV and IIR (R=-0.24), but this showed a greater correlation in those patients who have the least dilated LA (p = 0.02). Conclusions LGE-MRI and EAM showed good correlation in delineating potential pathologic substrate in AF, but left atrium dilation could reduce the performance of the CMR in this task. Conduction velocity could be more sensitive than voltage and LGE-MRI to detect incipient substrate in AF. Voltage and conduction velocity values Area /IIR Velocity (mm/ms) Voltage (mV) I / <.20 1.036(0.913-1.158) 1.593(1.489-1.696) 2 / ≥1.20 and <1.32 0.722(0.590-0.850) 0.792 (0.649-0,935) 3 / ≥1.32 0.623(0.473-0,733) 0.444(0.245-0.642) Voltage and conduction velocity values in the three areas of the LGE-RMN. Abstract Figure. Correlation among voltage, VC and LA

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Atrial Fibrosis: Translational Considerations for the Management of AF Patients

Arrhythmia & Electrophysiology Review ◽

10.15420/aer.2018.79.3 ◽

2019 ◽

Vol 8 (1) ◽

pp. 37-41 ◽

Cited By ~ 2

Author(s):

Stylianos Tzeis ◽

Dimitrios Asvestas ◽

Panos Vardas

Keyword(s):

Left Atrial ◽

Rhythm Control ◽

Interventional Treatment ◽

Atrial Fibrosis ◽

Controlled Clinical Trials ◽

Gadolinium Enhancement ◽

Rate Versus ◽

Voltage Mapping ◽

Left Atrial Fibrosis ◽

Randomised Controlled

Fibrosis plays a fundamental role in the initiation and maintenance of AF, mainly due to enhanced automaticity and anisotropy-related re-entry. The identification and quantification of atrial fibrosis is achieved either preprocedurally by late gadolinium enhancement MRI or intraprocedurally using electroanatomic voltage mapping. The presence and extent of left atrial fibrosis among AF patients may influence relevant decision making regarding the need for anticoagulation, the adoption of rate versus rhythm control and mainly the type of ablation strategy that will be followed during interventional treatment. Several types of individualised substrate modifications targeting atrial fibrotic areas have been proposed, although their impact on patient outcome needs to be further investigated in adequately powered prospective randomised controlled clinical trials.

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